The invention relates to scroll compressors, and more particularly to a venting structure for an oil pump in the scroll compressor.
Scroll compressors are widely used in refrigerant compression applications. A scroll compressor typically includes two interfitting scroll members. Each scroll member has a base with a generally spiraling scroll wrap extending from the base. The wraps interfit to define a plurality of compression chambers. One scroll member acts as a non-orbiting scroll member while the other scroll member acts as an orbiting scroll member and orbits relative to the non-orbiting scroll member. The relative rotation causes the wrap in the orbiting scroll member to orbit relative to the wrap in the non-orbiting scroll member, changing the volume of the compression chambers. This changing volume compresses refrigerant trapped in the compression chambers.
An input shaft driven by a motor rotates the orbiting scroll member. The input shaft has an oil supply passage extending along its length. The lower portion of the input shaft is mounted to a bearing structure having one or more inlets that fluidically couple the oil supply passage in the shaft with an oil supply that often contains some liquid refrigerant dissolved in it. A thrust washer placed between the input shaft and the bearing structure has an opening to allow fluid to reach the input shaft. Because the inlets are spaced apart from the thrust washer, however, the fluid flow through the inlets may generate low pressure zones around the inlets.
The refrigerant dissolved in the oil supply is often in a liquid state that is just below its vaporization point. Sudden drops in pressure, such as in the low pressure zones, causes the dissolved refrigerant to vaporize, creating bubbles in the oil around the bearing structure. These bubbles interfere or interrupt oil flow and can potentially cause bearing damage.
There is a desire for an oil pump structure that prevents low fluid pressure areas from forming around the bearing structure.
Accordingly, the present invention is directed to an oil pump configuration having a vented bearing member. The vent is disposed between at least one fluid inlet in the bearing member and a thrust washer placed between the bearing member and an input shaft in the pump. The vent equalizes fluid pressure by reducing or eliminating potential low pressure zones caused by fluid separation within the bearing member.
In one embodiment, the vent is vertically aligned with the fluid inlet. In another embodiment, the vent may be staggered above and between two inlets. In both embodiments, the vents may be placed in any position between the thrust washer and the inlets, including directly beneath the thrust washer.